1. Field of the Invention
The present invention relates generally to an oil-retaining bearing fan device, and more particularly to an oil-retaining bearing fan device including at least one magnetic member. The magnetic member serves to apply a magnetic attraction force to a shaft of the fan device to make the shaft quickly restore to its optimal operation position so as to reduce wear and lower the noises and vibration of the fan device in operation. Therefore, the lifetime of the fan device can be prolonged.
2. Description of the Related Art
Recently, all kinds of electronic information products (such as computers) have been more and more popularly used and widely applied to various fields. There is a trend to increase processing speed and expand access capacity of the electronic information products. Therefore, the electronic components of the electronic information products have operated at higher and higher speed. When operating at high speed, the electronic components generate high heat at the same time.
With a computer host taken as an example, the central processing unit (CPU) in the computer host generates most of the heat generated by the computer host in operation. In case the heat is not efficiently dissipated, the temperature of the CPU will rise very quickly to cause deterioration of the execution efficiency. When the accumulated heat exceeds a tolerable limit, the computer will crash or even burn down in some more serious cases. Moreover, for solving the problem of electromagnetic radiation, the computer host is often enclosed in a computer case. This will affect the dissipation of the heat generated by the computer host. Therefore, it has become a critical issue how to quickly conduct out and dissipate the heat generated by the CPU and other heat-generating components.
Conventionally, a heat sink and a cooling fan are arranged on the CPU to quickly dissipate heat. One side of the heat sink has multiple radiating fins, while the other side of the heat sink is free from any radiating fin. The surface of the other side of the heat sink directly contacts the CPU for conducting heat to the radiating fins. The radiating fins serve to dissipate the heat by way of radiation. In addition, the cooling fan cooperatively forcedly drives airflow to quickly carry away the heat.
FIG. 1 is a perspective sectional assembled view of a conventional oil-retaining bearing cooling fan. The cooling fan 1 includes a fan base seat 11. A bearing cup 111 protrudes from the fan base seat 11. A bearing 12 is disposed in the bearing cup 111. A fan impeller 13 is assembled with the fan base seat 11. The fan impeller 13 has multiple blades 131 annularly arranged along outer circumference of the fan impeller 13. The fan impeller 13 further has a shaft 132 extending from an inner side of the fan impeller 13. The shaft 132 is disposed and located in the bearing 12. An oil film 121 is filled between the bearing 12 and the shaft 132. The relative position between the fan base seat 11, the bearing 12 and the fan impeller 13 is tested and adjusted to an optimal operation position where the shaft 132 of the cooling fan 1 can stably rotate within the bearing 12 under support of the oil film 121. Accordingly, in operation of the cooling fan 1, the shaft 132 rotates within the bearing 12 in an operation position relative to the bearing 12 only under the support force of the oil film 121. However, the support force of the oil film 121 provided for the shaft 132 is smaller than the eccentric force applied to the shaft 132 in operation of the cooling fan 1. Therefore, the shaft 132 and the bearing 12 will still abrade and collide each other. Also, in case the cooling fan 1 is collided by an alien article to make the shaft 132 deflected from its true position, the shaft 132 will collide the bearing 12 and vibrate in operation. Under such circumstance, in operation, the cooling fan 1 will vibrate and make noises due to the deflection of the shaft 132. Moreover, the wear between the shaft 132 and the bearing 12 will be increased to shorten lifetime of the cooling fan 1. The shaft 132 may be restored to its optimal operation position under the support force of the oil film 121. However, after squeezed, it takes longer time for the oil film 121 to recover so that the shaft 132 also needs longer time to restore to its optimal operation position. As a result, the noises will last longer.
According to the above, the conventional oil-retaining bearing cooling fan has the following shortcomings:                1. The conventional oil-retaining bearing cooling fan tends to vibrate and make noises.        2. The conventional oil-retaining bearing cooling fan is more subject to wear.        3. The noises made by the conventional oil-retaining bearing cooling fan will last longer.        4. The lifetime of the conventional oil-retaining bearing cooling fan is shorter.        